Friedreigh's ataxia (FRDA) is the most common autosomal recessive neurodegenerative disease among Caucasian populations. FRDA is characterized by the early onset of the disease usually before the age of 25, a progressive ataxia, sensory loss, absence of tendon reflexes and pyramidal weakness of the legs (Friedreich N, Virchows Arch. Pathol. Anat., 68, 145-245 (1876); Freidreich N, Virchows Arch. Pathol. Anat., 70, 140-142 (1877); Harding, A. E., Brain 104, 589-620 (1981); Durr, A. et al., N Engl J Med 335, 1169-75 (1996)). FRDA is known to be caused by a mutation of a gene on chromosome 9q13.
The inventor has recently identified a patient group which is characterized by autosomal recessive inheritance, early age of onset, FRDA-like clinical presentations, and hypoalbuminemia. Linkage of a causative gene of this disease to the FRDA locus was excluded by linkage analysis.
The clinical presentations of this disease were similar to those of a disease, which is called “ataxia with oculmotor aprataxia, AOA” linked to 9p13 (do Ceu Moreira, M et al., Am J Hum Genet 68, 501-8 (2001)).
The causative gene for the disease, which the inventor has found has not yet been identified. Therefore, diagnosis of this disease has been based only on clinical observations.